.calculator {
  display: inline-block;
  font-size:20px;
}
.calculator .button {
  width: 6em;
  height: 6em;
}

.calculator .button.text-clear {
  width: 18em;
}

.calculator .button.text-0 {
  width: 12em;
}

.calculator .output {
  border: 1px solid grey;
  height: 6em;
  position: relative;
}

.calculator .output span {
  position: absolute;
  bottom: 4px;
  right: 4px;
  font-size: 2em;
}
